1. Field of the Invention
This invention relates to coated woven textile fabrics for use in an air-holding vehicle occupant restraint system and, more particularly, to a multi-layered woven fabric having preconfigured air-holding cavities and a plurality of polymeric layers coated thereon.
2. Description of the Related Art
Presently known restraint systems for vehicles include driver and passenger side air bags which are housed in the steering wheel and in the dashboard, respectively, in a collapsed, folded condition and are adapted to be deployed instantaneously by introduction of a gasxe2x80x94sometimes referred to herein as xe2x80x9cairxe2x80x9dxe2x80x94upon the occurrence of a collision. The automotive industry has recently introduced air bags which are housed in the rear supports of the front seats or in the rear seats to protect the cabin occupants in the event of a collision occurring on either side of the vehicle. More recently, a further safety feature that has been made available for passenger vehicles, especially the so-called sport utility vehicles (SUV), are air-holding side impact protective inflatable side curtains which are designed to provide a cushioning effect in the event of rollover accidents. These side curtains are housed uninflated in the roof of the vehicle or in one of the main support pillars of the vehicle and deploy along the interior sidewalls of the cabin of the SUV in the event of a rollover.
One technique for improving the efficacy of air-holding capability in vehicle restraint systems has addressed the coatings to be applied to the textile substrate to improve air retention. In the prior art, coated air bags were made by coating a nylon substrate with silicone rubber and chloroprene. These coated air bags, however, were not susceptible to heat sealing. In order to ameliorate some of the problems inherent in chloroprene and silicone rubber coatings, it has been disclosed in the art, for example, in Menzel et al., U.S. Pat. No. 5,110,666, to coat a woven nylon substrate with polyurethane to provide the desired permeability to better retain the inflation gas. Certain aqueous silicone emulsion coating compositions that yield a tack-free surface and high mechanical strength to prevent cracking on inflation of the air bag have also been disclosed in the art, such as is disclosed, for example, in Inoue et al., U.S. Pat. No. 5,254,621.
Despite the advances in air bag coating technology, the problems of controlling air permeability, air pressure, and volume still remain. For example, one particular cause of air loss arises out of the fact that during the manufacture of the air bags, they are often stitched together by conventional sewing procedures which utilize sewing threads. Each stitch inherently creates a potential gas leak that adversely affects the integrity and, hence, the air holding capability of the bag, especially when instantaneous deployment of an operative air bag is required. Moreover, such vehicle occupant restraint systems often require great amounts of cutting, stitching and sealing in their production. I have invented a coated flexible multi-layered textile fabric for air-holding vehicle devices which can be heat sealed to withstand inflation pressures in such inflatable restraint systems in a controlled and improved manner, while minimizing the amount of cutting and sealing actually required.
It has been found that by applying a plurality of polymeric polyurethane and/or polysiloxane coating layers to a woven textile fabric substrate having preconfigured air-holding cavities, an air-holding vehicle restraint system is obtained that has superior air holding characteristics, viz., permeability, volume and pressure retention. Further, if a multi-layered woven textile fabric substrate having top and a bottom surfaces is first coated on both surfaces with an adhesive polyurethane layer and, thereafter, the adhesive polyurethane layer is coated with a layer of an elastomeric polyurethane or an elastomeric polysiloxane, the air bag formed therefrom has superior air holding permeability and volume, and, in the case of polysiloxane, also possesses superior heat resistance. Since silicone is inert, it will not block or stick to itself while housed in the vehicle, even during extended periods of non-use, but will nonetheless deploy in an efficient and rapid manner when the need arises to provide the required protection in the event of a collision.
The invention relates to a coated textile substrate for an air-holding vehicle restraint system, which comprises a multi-layered textile substrate having opposed outer surfaces, a first coating layer of an adhesive polyurethane on a first surface of the multi-layered textile substrate, and at least a second coating layer of an elastomeric polysiloxane on the first coating layer. In one preferred embodiment, the invention relates to a coated textile fabric for an air-holding vehicle restraint system, which comprises, a multi-layered textile substrate having first and second opposed outer surfaces and preconfigured air-holding cavities therein, at least a first coating layer of adhesive polyurethane coated on both the first and second opposed outer surfaces of the textile substrate, and at least a second coating layer of a polymeric material coated on both of the first coating layers of adhesive polyurethane.
The multi-layered textile substrate is preferably a fabric constructed from synthetic material, preferably selected from the group consisting of polyamides and polyesters. In the preferred embodiment, the coated textile substrate is a woven nylon fabric, and the first coating layer is selected from the group consisting of aromatic or aliphatic polyester and polyether polyurethanes. The second coating layers are each coated with a third coating layer of elastomeric polyurethane or polysiloxane. Preferably, one of the first coating layers is coated with a second coating layer of elastomeric polyurethane and the other first coating layer is coated with a second coating layer of polysiloxane.
In a preferred embodiment, a coated textile fabric for an air-holding vehicle restraint system is disclosed, which comprise, a multi-layered woven fabric substrate having first and second opposed outer surfaces and preconfigured air-holding woven cavities defined between the fabric layers, at least a first coating layer of adhesive polyurethane coated on both the first and second outer surfaces of the textile substrate, at least a second coating layer of elastomeric polyurethane or polysiloxane coated on the first coating layers of adhesive polyurethane, and at least a third coating layer of a polymeric material coated on at least one of the second coating layers.
The coated woven textile substrate is preferably a fabric constructed from synthetic material, wherein the synthetic material is a synthetic filamentary material selected from the group consisting of polyamides and polyesters. Also, the woven textile substrate is preferably comprised of woven nylon filaments. The first coating layers are preferably selected from the group consisting of aromatic or aliphatic polyester or polyether polyurethanes. The first coating layers are preferably coated with a second coating layer of elastomeric polyurethane.
One of the first coating layers may be coated with a second coating layer of elastomeric polyurethane and one of the other first coating layers is coated with a second coating layer of polysiloxane. The second coating layer of elastomeric polyurethane may be coated with a third coating layer of elastomeric polyurethane, and the second coating layer of polysiloxane may be coated with a third coating layer of polysiloxane. The second coating layer of elastomeric polyurethane is preferably coated with a coating layer of elastomeric polyurethane, and the second coating layer of polysiloxane is preferably coated with a third coating layer of polysiloxane. The second coating layer of polyurethane is preferably coated with a third coating layer of elastomeric polyurethane and the second coating layer of polysiloxane is preferably coated with a third coating layer of polysiloxane.
Preferably, the first coating layers of adhesive polyurethane each have a coating weight of from about 0.3 ounces/sq. yd to about 1.5 ounces/sq. yd. Further, the coating weight is preferably about 0.5 ounces/sq. yd. The second coating layer is preferably an elastomeric aliphatic or aromatic polyether or polyester polyurethane having a solids content of from about 30% to about 100% by weight and preferably weighs about 1 ounce/sq. yd. to about 8 ounces/sq. yd, and preferably about 2 ounces/sq. yd. The third coating layer is preferably an elastomeric aromatic or aliphatic polyether or polyester polyurethane having a coating weight of from about 0.2 ounces/sq. yd. to about 2.0 ounces/sq. yd.
A method of coating a textile substrate for an air-holding vehicle restraint system is disclosed, which comprises, coating an adhesive polyurethane to a first surface of a multi-layered textile substrate having opposed surfaces and drying at an elevated temperature to form a first coating layer, coating an elastomeric polyurethane to said adhesive polyurethane coating layer and drying at an elevated temperature to form a second coating layer, and coating a polyether or polyester polyurethane to the second polyurethane coating layer and drying at an elevated temperature to form a third coating layer. The multi-layered textile substrate is a fabric constructed from synthetic fibers selected from the group consisting of polyamides and polyesters. The multi-layered textile substrate is a woven multi-layered fabric having opposed layers forming preconfigured pockets having air-holding cavities, the pockets being connected by fabric web connectors formed at least in part of fabric portions of dual thickness and fabric portions of opposed fabric layers stitched together at predetermined locations. The multi-layered textile substrate is preferably woven from nylon filaments.
A method of forming an air-holding restraint system for a vehicle is also disclosed, which comprises, coating an adhesive polyurethane to a first surface of a multi-layered textile substrate to form a first coating layer, coating an elastomeric polyurethane to the first coating layer to form a second coating layer, coating a top-coating of a polyester or polyether polyurethane to form a third coating layer, repeating steps (a), (b), and (c) on a second surface of the multi-layered textile substrate, and sealing the first and second coated textile substrates together by radio frequency sealing, hot air sealing or ultrasonic sealing.
A preferred method of forming an air-holding restraint system for a vehicle is also disclosed, which comprises, coating an adhesive polyurethane to a first surface of a multi-layered textile substrate to form a first coating layer, coating an elastomeric polysiloxane to the first coating layer to form a second coating layer, repeating coating steps a) and b) on a second surface of the multi-layered textile substrate, and sealing the coated textile layers together by radio frequency sealing, hot air sealing or ultrasonic heat sealing.